Backup Problem

I received an error message that my backup wouldn't run because I needed more storage.  I had 25 gb.  I purchased an additional 10 gb and, instead of telling me I now had 10 gb of 35 gb, the message now says I have 0 gb of 35 gb.

I deleted files from my default back up set, and it is now 18 gb.  I also slimmed down what I want to back up, and it is now 1.4 gb.

This looks like a Norton bug to me.  What is happening and why doesn't my backup work?